Revert "pythonPackages.setuptools: make compatible with hasPythonModule"

The packages with this change can not be evaluated with `nix-env --drv-path` or
`hydra-eval-jobs`: https://github.com/NixOS/nixpkgs/commit/859dc02fa3f42bca9b7770eb96f4fd8224cf1576

This reverts commit 859dc02f.